In recent years, displays of image display devices including television receivers are shifting from conventional cathode-ray tube displays to thin-screen displays including liquid crystal panels and plasma display panels. With the thin-screen displays, thin image display devices can be provided. A liquid crystal display device requires a backlight unit as a separate lighting device because a liquid crystal panel used therein is not a light-emitting component.
A technology to provide thin liquid crystal display devices is disclosed in Patent Document 1. A backlight unit disclosed therein includes LEDs and light guide plates. Each LED has a light-emitting surface through which light is emitted in the direction substantially parallel to a display surface of a liquid crystal panel. Each light guide plate has a light entrance surface in a side area (a side-edge area) and a light exit surface on a top surface. A lower surface of each light guide plate, that is, a surface opposite from the light exit surface has scattering patterns for scattering light and a reflection sheet for reflecting light. With such patterns and reflection sheet, uniform in-plane brightness distribution is achieved on the light exit surface.    Patent Document 1: Japanese Published Patent Application No. 2006-108045